Solenoid operated valve with provision for safe failure



Jan. 6, 1959 c. J. KLEIN 2,867,236

SOLENOID OPERATED VALVE WITH PROVISION FOR SAFE FAILURE Filed April 6, 195a aasawc:

IN VEN TOR.

Arron/4r United States SOLENOID OPERATED VALVE WITH PROVISION F OR SAFE FAILURE Clarence J. Klein, South Bend, Ind., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application April 6, 1956, Serial No. 576,711

8 Claims. (Cl. 137--=623) The present invention relates to fluid pressure control devices and, more particularly, to an electrically actuated valve structure for controlling servo pressures which has a provision for insuring safe failure.

In designing servo systems, especially for use on aircraft, it is often necessary that some means be provided for controlling the application of a relatively high fluid pressure against a control piston or other member. In many cases, it is essential that, if a member has been subjected to a high servo pressure and has, as a result, been moved to a certain position, it must remain in that position and not seek a new or former position as a result of a loss of electrical power. It is accordingly an object of the present invention to provide an electrically actuated device for controlling servo pressures which will maintain a safe position even though electrical power is lost.

It is another object of the present invention to provide an electrically actuated fluid pressure controlling device in which the movable members may be permitted to operate immersed in fluid.

It is another object of the present invention to provide a device which will accomplish the above objects and which is so designed as to have great resistance to damage or malfunctioning from shock, vibration, or contamination of the operating fluid. It is a further object to provide a device which will accomplish the above objects and which is capable of being constructed in a very small and comparatively light package.

, Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawing, in which the single figure shows a cross sectional view of my control device in combination with a schematic representation of the associated switching circuit.

Referring to the drawing, a housing is shown generally at numeral 10 having an inlet port 12 communicating with a source of high fluid pressure supplied by a pump 13, a servo outlet port 14 communicating with a power piston 15 and an outlet port 16 which communicates with the low pressure side of the servo pressure source. Within a housing 10 is a chamber 18 having permanently positioned therein a member 20 having a series of ports 22, 23, 24 and 25 and a pair of valve seats 26 and 28. Fluid flowing into housing 10 through inlet port 12 enters an annular chamber 30, passes through a series of orifices 32 entering a chamber 34. From chamber 34 the fluid is in communication with the interior of member 20 through passage 22. Positioned within member 20 and arranged to move axially therein against either seat 26 or seat 28 is a valve member 36. This valve is actuated through a shaft 38 having positioned thereon a collar 40 and a stop 42. Stop 42 is urged against a face of an annular spring retaining member 44 through the action of a spring 46. The other end of spring 46 exerts a force against an annular spring retainer member 48 threadedly engaged with a soft iron armature 50. It will thus be seen from the foregoing that spring 46 acting through retainer 44 and stop member 42 exerts a force urging member 38 and hence valve 36 to the right. Armature 50, which is a hollow cylindrical soft iron member, carries with it a permanent magnet member 52 and both armature 50 and magnet 52 are adapted to abut against a soft iron pole member 54. A spring 56 tends to urge armature 50 and magnet 52 away from the face of pole member 54. Housing itlhas a large cylindrical indentation 58 which carries a primary winding 60 positioned concentrically with respect to armature 50 and pole member 54 and also a secondary winding 62 wound around the outside of winding 60. The leads from windings 60 and 62 are drawn through a pair of Teflon liners 64 and 66 positioned in channels drilled in member 54. These leads are fastened as shown to a standard connector shown generally at member 68.

The windings 60 and 62 are connected to an electrical switching circuit shown schematically on the drawing in which one lead from winding 62 is connected to a wire 70 and a stationary contact 72 forming part of a switch 73. Winding 60 is connected through a lead 74 to a stationary contact 75. The opposite terminals of each of windings 60 and 62 are connected through the center contact of connector 68 and a wire 76 to ground. A movable contact 78 of the switch is connected to a direct current source. It will be observed from the foregoing that either winding 66 or winding 62 may be energized through manipulation of movable contact 78, but that at no time are both windings energized. A resistor 82 is connected between wires 74 and 76 in such manner that it effectively forms a shunt across the primary winding 6%. The function of this resistor will be discussed below in relation to the operation of my invention.

It is the function of the device herein described to control the flow of servo fluid at a comparatively high pressure to the controlled power piston 15 downstream of outlet port 14. As shown in the drawings, valve 36 is held against seat 28, servo fluid will flow into port 12 and chamber 30 through orifices 32, into chamber 34 through passages 22, 23, and out of port 14. This may be considered the normal or non-energized position of my device. Upon energization of winding 60 through the closing of movable contact 78 on stationary contact 75, a magnetomotive force will ensue causing a flux path linking housing 10, armature 59, and pole member 54. This force will cause armature 50 to move toward the right thus abutting against the face of pole member 54 against the action of spring 56. As armature 50 is moved to the right, it carries with it member. 48, spring 46, retainer 44, shaft 38, and hence, valve 36, which will be urged against seat 26 on the right end of member 20 thereby interrupting communication between ports 12 and 14 and opening communication between ports 14 and 16. This will result in a sharp reduction in servo pressure against power piston 15 downstream of port 14 permitting .it to move to the right. The above members are so arranged thatvalve member 36 will contact seat 26 before armature 50 reaches pole member 54. Movement of armature 50 after valve member 36 is seated simply re sults in compressing of spring 46. This lost motion structure insures that valve member 36 will seat even though Wear occurs on either valve 36 or seat 26. Should electrical power fail and winding 60 no longer be energized, the armature 56 will remain held against pole member 54 through the action of permanent magnet 52. Should it be desired to return the valve 36 to its position as shown in the drawing, it is necessary that movable contact 78 be switched against stationary contact 72 so that secondary winding 62 can be energized. Upon energization of the secondary winding, a magnetomotive force is produced which effectively counteracts that pro- Fatented Jan. 6, 1959- duced by the armature magnet 52 and allows the armature to move'to the left through the'action or spring 56; thus moving valve 36 against seat 28.

The amount of current supplied to secondary winding 6 2,,must be: just. suflicient to-temporarily overcome the, effect oftpermanent magnet 52 and must not be enough to cause: an .actual reyers'alof polarity of the permanent magnet It ispossible; however,.in any applicationwhere power supplies are not precisely regulated that voltage surges could be. impressed on this winding several. times larger than-is desired. ResistorSZhasbeen placed across the. primary Winding in order tolmeetthis problem. It will be recognized that there will be a transformer action, taking. place between the windings 6t). and 62 and that} the greater the voltage surge occurring in winding 62,'the greater Will. be thecorresponding increase in voltage across winding fitl. The resistonSZ- provides a relatively low impedance path across Winding 60- which prevents the translation. of these voltage surges into-a magnetomo'tive force which would effectively reverse the polarity of magnet 52.

While only one embodiment has been shown and described herein, modifications and changes in sizeand relationship of parts maybe made to suit requirements.

I claim:

1. In a fluidpressure control device comprising a hollow. cylindrical housing, an. inlet port in said housing connected with a source of. fluid under pressure, a first outlet port connected to a servo system, a second outlet port in communication with a source of low fluid pressure andv a valve member operable to block communication between said outlet ports and permit communication-between said inlet port and said first outlet port when in one position and to block communication between said inlet port and said first outlet port and permit communication between said outlet ports when in another position: means controlling the position of said valve including a 'soft iron pole member positioned within said housing in such manner as to close one end of said housing, a hollow cylindrical soft iron armature resiliently attached to said valve and movable axially in said housing toabut against said polemembena cylindrical permanent magnet positioned within said armature, a spring positionedbetween said armature and said pole member, a first winding embedded in said housing and positioned concentrically with respect to said pole member and said armature, said windingbeing moved in such-direction that, uponenergization, the magnetomotive force developed therebyurges said armature toward said pole piece,; a. second winding positioned concentrically with respect to said first winding and, wound so that upon energization a magnetomotive force is produced opposing the; first named magnetomotive force.

2. A fluid pressure control device comprising a housing,- an inlet port in said housing, first and second outlet ports in said housing, a valve member operable to block communication between said outlet ports and permit communication between saidinlet portand one of said outlet ports when in one position and to block communication between said inlet port and said outlet ports and permit communicationbetween said outlet ports whenin another position, a pole member positioned in one end of'said housing, an armature resiliently attached to saidvalve and movable axially in said housing, a permanent magnet positioned within said armature, resilient means positioned between said armature andsaid pole member, a first winding positioned concentrically with respect to said pole-member andsaid armature" which; whenenergized; produces a magnetomotive force urging said armature toward said pole piece, a second winding positioned concentrically with respect to said first winding which, when energize-d, produces a magnetomotive force opposing the first named magnetomotiveeforcee 3. A fluid pressure control device as set forth in claim 2 whereina resistor is connected across saidscondwind= ing, and a switch is connectedto both of said windings in such manner that one or the other of. said windings, may be energized.

4. A fluid pressure control device comprising a housing, a plurality of ports in said housing, a valve member in said housing operable to block communicationbetweencertain of said ports when in, one position, and between certain other of said ports when in another position, a pole member positioned in one end of said housing, an armature operably connected to said valve and. adapted to reciprocate in said housing, a spring positioned between said armature and said pole member, a first winding which when energized produces a first magnetomotiveforce urging said armature toward saidpole piece, a, permanentmagnet operably associated with said armature producing -a force. whereby said armature, once placed in abutment with said pole, piece, is caused to remainv in abutment with said pole piece against the force of said spring even though said first winding becomes de-energized and a. second winding which, when energized, produces a mag netomotive force opposing that. produced by said permanent magnet. I

5. A fluid pressure control device as set vforth in claim 4 wherein a-resi'stor is connected across said second Winding, and a switch. is, connected to both. of said windings. in such manner that one or the other of said. windings may be energized.

6. In a fluid-pressure control device including, a con-. duit connected to a source of fluid under. pressure, a valve member positioned in said conduit in suchmanner that when in one position communication is interrupted and whenin, another position communication is permitted;

through. said conduit: means. controlling. said' valve, ,CQIl'lr. prising an armatureoperably connected to said valve,, a, first winding in inductive relation with said armature,

which when energizedv produces a magnetomotive force.

tending to move said valve, to one of said positions, a permanent magnet associatedwith said armature producingta magnetomotive. forcewhereby said. armaturesiss.

caused to remainin said one position even thougl i saidj. winding becomes de-energized and asecondv winding, which when energized produces a magnetomotive forcel opposing that produced by said permanent. magnet.

7. A fluid pressure control device as set. forth in claim 6 wherein said connection between saidvalve andsaid armature includes a resilient member.

8. A fluid. pressure control device as set forth in claim. 6 wherein a resistor, is connected across saidsecond winding, and aswitchis connectedto bothaof saidjwindfings in such, mannerthat one or the other of said windings may be energized.

References Cited in'the fileof this patent- UNITED STATES: PATENTS 

